Machined fan exit guide vane attachment pockets for use in a gas turbine

ABSTRACT

The present invention relates to an improved system for installing a vane in a gas turbine. The system includes a receptor pocket positioned within a first support structure and a boot attached to a first or inner end of a vane for insertion into the receptor pocket. In a first embodiment of the present invention, the receptor pocket is formed by machining it into the support structure. In a second embodiment of the present invention, the receptor pocket is formed by an insert which is installed into the support structure. In accordance with the present invention, the inner end of the vane having the boot is first inserted into the receptor pocket. After insertion has been completed, the vane is rotated until an outer base is brought into position against an outer support structure. The outer end of the vane is then secured to the outer support structure using studs and nuts.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an improved fan exit guide vaneinstallation system for use in gas turbines.

[0002] In a gas turbine engine used for propulsion, a fan case and asmaller diameter compressor case cooperate to radially bound an annularfan duct. Fan exit guide vanes span across the fan duct to de-swirlworking medium fluid flowing therethrough. The outer and innerextremities of the vanes are connected to the fan and compressor casesrespectively. Traditionally, the outer connection is effected by a pairof bolts. The inner connection, by contrast, includes numerous partsincluding spacers, nuts, bolts, and inserts.

[0003] This type of system presents problems from a replacement ormaintenance standpoint. Occasionally, a vane will become damaged in useand need to be replaced. Using the connection system described above,replacement of a single damaged vane is difficult. In U.S. Pat. No.5,690,469 to Deal et al., the issue of replacing a vane is addressed. Inthis patent, a repair kit for replacing an unserviceable vane assemblyis described. The repair kit includes a serviceable vane subassemblyhaving a serviceable airfoil with a base attached to the root end and anopposing base which is unattached to, but slidably engagable with theserviceable airfoil. The opposing base is slipped over the tip end ofthe airfoil and slid toward the base attached to the root end. The vanesubassembly and opposing base are pivoted into position between innerand outer engine cases in place of an unserviceable vane assembly sothat sockets in the attached base engage support pins extending from theinner case. An adhesive is applied to the tip end of the serviceableairfoil and the opposing base is translated into its installed positionnear the tip end of the serviceable airfoil. Upon curing of theadhesive, the opposing base becomes attached to the airfoil. The base issecured to the outer case by studs and nuts.

[0004] There is a need for a simpler system for installing fan exitguide vanes which reduces the quantity of parts, the cost of the parts,and the weight of the parts. There is also a need for a simpler systemwhich facilities the repair of damaged vanes.

SUMMARY OF THE INVENTION

[0005] Accordingly, it is an object of the present invention to providean improved system for installing a vane such as a fan exit guide vaneto a support structure in a gas turbine.

[0006] It is a further object of the present invention to provide asystem as above which has a reduced quantity of connection parts andreduced weight.

[0007] It is a yet another object of the present invention to provide aneconomically beneficial installation system.

[0008] The foregoing objects are attained by the system of the presentinvention.

[0009] In accordance with the present invention, a system for installinga vane broadly comprises a structure for supporting an inner end of avane, a receptor pocket in the support structure, and a boot attached toa first or inner end of the vane for insertion into the receptor pocket.In a first embodiment of the present invention, the receptor pocket ismachined into the support structure and is preferably open-ended andcurved in configuration. The boot is preferably formed from a resilientdampening material, such as silicone rubber, and has a depth greaterthan the depth of the receptor pocket in the support structure.

[0010] In an alternative embodiment of the system of the presentinvention, an opening is machined into the support structure and aninsert is placed into the opening to act as the receptor pocket. Toinstall a vane, the boot on the vane is placed in the insert. The insertis provided with a flange portion which rests on a peripheral ledgemachined in the support structure. The peripheral ledge maintains anupper surface of the flange portion substantially flush with an uppersurface of the support structure. Retention devices may be used to holdthe insert within the opening.

[0011] Other details of the installation system of the presentinvention, as well as other objects and advantages attendant thereto,are set forth in the following detailed description and the accompanyingdrawings in which like reference numerals depict like elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 illustrates a portion of a gas turbine engine having a vaneinstalled in accordance with the present invention;

[0013]FIG. 2 illustrates a support structure having machined receptorpockets used in the system of the present invention;

[0014]FIG. 3 is a top view in partial section of a vane installed in asupport structure;

[0015]FIG. 4 is a sectional view taken along lines 4-4 in FIG. 3;

[0016]FIG. 5 is a perspective view of a vane used in the system of thepresent invention;

[0017]FIG. 6 is a top view in partial section of an alternative mannerfor installing a vane in a support structure in accordance with thepresent invention;

[0018]FIG. 7 is a sectional view taken along lines 7-7 in FIG. 6;

[0019]FIG. 8 is a sectional view taken along lines 8-8 in FIG. 6;

[0020]FIG. 9 is a sectional view taken along lines 9-9 in FIG. 6; and

[0021]FIG. 10 is a perspective view of a portion of a fan exit guidearray attached to inner and outer support structures in accordance withthe installation system of FIGS. 2-5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0022] Referring to FIG. 1, a gas turbine engine 10 of the type used foraircraft propulsion includes a fan section 12 having an array of fanblades such as representative blade 14 extending radially outwardly froma hub 18. The hub and blades are rotatable about an engine axis. The fanalso includes an array of fan exit guide vane assemblies, such asrepresentative guide van assembly 24, which extend radially betweeninner and outer cases 26 and 28 respectively, whose axes are common withthe engine axis. A fan flowpath 38 extends through the fan section and aworking medium fluid, such as air, flows through the flowpath in thedirectly generally indicated by directional arrow 40.

[0023] As shown in FIG. 5, each fan exit guide vane 24 in the array offan exit guide vanes has an outer end with an integrally formed outerbase 42. The outer base has a platform 44 and a sleeve 46. Typically, apolyurethane material 48 is disposed within the sleeve 46. Thepolyurethane material serves to damp vibrations in the vane and theoverall assembly. Threaded studs 49 project outwardly from the outerbase 42 and extend through holes 50 into the outer case 28. Nuts 51,threaded onto the studs 49, positively secure the outer base 42, andtherefore, the outer end of a respective vane 24 to the outer case 28.

[0024] The inner end of each fan exit guide vane 24 in the array of fanexit guide vanes is attached to an inner support structure such as anannular ring portion 60 which forms part of the inner case 26. Inaccordance with the a first embodiment of the present invention, theannular ring portion 60 is provided with an array of open-ended receptorpockets 62 machined therein. The array of receptor pockets 62 extendsaround the circumference of the ring portion 60 with respective ones ofthe pockets receiving the inner ends of respective fan exit guide vanes24. As can be seen from FIG. 2, each receptor pocket 62 has arcuatelyshaped sidewalls 64 and 66 which conform to the shape of the inner endof the vane 24.

[0025] Referring now to FIGS. 3-5, the inner end of each vane 24 has aboot 70. The boot 70 may be formed integrally with the vane 24 or may beformed separately from the vane 24 and attached thereto using anysuitable adhesive means known in the art. The boot 70, as can be seenfrom FIGS. 3 and 4, is configured to fit securely within one of thereceptor pockets 62.

[0026] The boot 70 is preferably formed from a resilient dampeningmaterial, such as silicone rubber, to help absorb vibrations. The boot70 preferably has a depth which is greater than the depth of thesidewalls 64 and 66 of a receptor pocket 62 into which it is to beinserted so as to firmly secure the inner end of the vane 24 into thereceptor pocket 62.

[0027] To install a vane 24 using the system of the present invention,the inner end of the vane 24 with the boot 70 is inserted into areceptor pocket 62. The vane 24 is then rotated towards the outer case28 and the studs 49 and the nuts 51 are installed to secure the outerend of the vane 24 to the outer case 28.

[0028]FIG. 10 illustrates a portion of an array of fan exit guide vanes24 mounted to inner and outer casings 26 and 28 respectively. The innerends of the vanes 24 are installed using the system of FIGS. 2-5.

[0029] FIGS. 6-9 illustrate an alternative embodiment of a vaneinstallation system in accordance with the present invention. In thissystem, a series of openings 100 are machined into an inner supportstructure such as the annular ring portion 60 of the inner casing 26.Each of the openings 100 is provided with a peripheral ledge 102.

[0030] A receptor pocket for the inner end of the vane 24 is formed by aflanged insert 104, preferably in the form of a flanged cup insert. Ascan be seen from the drawings, the insert 104 has an outwardlyextending, peripheral flange 106 about its periphery. The insert 104 maybe formed from any suitable metallic or non-metallic material known inthe art. Preferably, it is formed from a plastic material such as nylon,polyurethane, or an elastomeric plastic material. For example, theinsert 104 could be formed from a nylon material having a graphitefiller.

[0031] As shown in FIG. 7, when the insert 104 is installed in theopening 100, the flange portion 106 rests on the peripheral ledge 102.As a result, the upper surface 108 of the insert 104 is substantiallyflush with the upper surface 109 of the annular ring portion 60.

[0032] To keep the insert 104 within the opening 100, a plurality ofretention devices 110 can be inserted between a respective side wall ofthe insert 104 and a respective side wall of the opening 100. Theretention devices 110 may comprise any suitable retention device knownin the art.

[0033] As can be seen from the drawings, the insert 104 has a depthwhich is greater than the depth of the opening 100. The depth of theinsert 104 preferably is such that the insert 104 secures the inner endof the vane 24 to the inner casing 26.

[0034] To install a vane 24 using this embodiment of the presentinvention, the boot 70 on a vane 24 is positioned within the insert 104.Depending on the depth of the insert 104, the bottom end 112 of the boot70 may be spaced from, or may be in contact with, the bottom surface 114of the insert 104. After the boot 70 has been positioned in the insert104, the vane 24 is rotated to bring the outer base 42 into contact withthe outer casing 28. As before, studs 49 and nuts 51 are then used tosecure the outer end of the vane 24 to the casing 28.

[0035] It has been found that an installation system in accordance withthe present invention provides a number of significant advantages overprior art installation systems. For example, the installation systempermits a tight fit to be maintained between the boot on each vane andthe sidewalls of each pocket 62 during cruise and take-off. This resultsin the absence of any substantial air leakage around the flowpath. Theinstallation system of the present invention uses fewer parts than priorinstallations, has a reduced cost associated with it, and a reducedweight. The installation system of the present invention also lendsitself to single vane replacement.

[0036] While the installation system of the present invention has beendescribed in the context of installing fan exit guide vanes in gasturbine engines used for propulsion, it should be apparent that thesystem of the present invention may also be used to install other typesof vanes in a gas turbine engine used for propulsion or in other typesof gas turbines.

[0037] It is apparent that there has been provided in accordance withthe present invention a machined fan exit guide vane attachment pocketfor a gas turbine which fully satisfies the means, objects, andadvantages set forth hereinbefore. While the present invention has beendescribed in the context of specific embodiments thereof, otheralternatives, modifications, and variations will become apparent tothose skilled in the art having read the foregoing description.Therefore, it is intended to embrace those alternatives, modifications,and variations which fall within the broad scope of the appended claims.

What is claimed is:
 1. A system for installing a vane in a gas turbinecomprising: a receptor pocket positioned within a first supportstructure; and a boot attached to a first end of said vane for insertioninto said receptor pocket.
 2. A system according to claim 1, whereinsaid boot is molded onto said vane.
 3. A system according to claim 2,wherein said boot is formed from a flexible dampening material.
 4. Asystem according to claim 3, wherein said boot is formed from siliconerubber and is contoured to fit said receptor pocket.
 5. A systemaccording to claim 1, wherein said first support structure is an annularring portion of an inner casing and said receptor pocket is machinedinto said annular ring portion.
 6. A system according to claim 5,wherein said receptor pocket has a curved configuration and said boothas a curvature which matches said curved configuration.
 7. A systemaccording to claim 6, wherein said receptor pocket machined into saidannular ring portion is open-ended and wherein said boot has a depthgreater than a depth of the receptor pocket.
 8. A system according toclaim 1, wherein a second end of said vane is secured to a secondsupport structure by a pair of bolts.
 9. A system according to claim 1,further comprising: said first support structure having an opening; saidreceptor pocket being formed by an insert installed in said opening; andsaid boot on said vane fitting into said insert.
 10. A system accordingto claim 9, wherein said insert comprises an insert cup.
 11. A systemaccording to claim 9, wherein said insert has an outwardly extending,peripheral flange portion and said first support structure is providedwith a peripheral ledge to accommodate said peripheral flange portion sothat an upper surface of said peripheral flange portion is substantiallyflush with a surface of said inner support structure.
 12. A systemaccording to claim 9, wherein said opening has a first depth and whereinsaid insert has a second depth greater than said first depth.
 13. Asystem according to claim 9, wherein said boot is formed from a flexibledampening material.
 14. A system according to claim 9, furthercomprising retention devices for retaining said insert within saidopening.
 15. A system according to claim 14, wherein each said retentiondevice is positioned between a side wall of said opening and a side wallof said insert.
 16. A vane for use in a gas turbine comprising: anairfoil structure having a first end and a second end; and a bootsurrounding a first end of the airfoil structure.
 17. A vane accordingto claim 16, wherein said boot is molded to said airfoil structure. 18.A vane according to claim 16, wherein said boot is formed from aflexible material.
 19. A vane according to claim 16, wherein said bootis formed from silicone rubber.
 20. A vane according to claim 16,wherein said boot is integrally formed with said vane.
 21. A vaneaccording to claim 16, further comprising an outer base adjacent anouter end of said airfoil and said outer base including a platform and asleeve.
 22. A method of installing a vane into a gas turbine comprisingthe steps of: providing an inner support structure having an openingmachined therein; providing a vane having a boot attached to an innerend; and attaching said vane to said support structure by positioningsaid boot in said opening.
 23. A method according to claim 22, furthercomprising inserting an insert cup into said opening and said attachingstep comprising inserting said boot into said insert cup.
 24. A methodaccording to claim 22, further comprising rotating said vane after saidattaching step and securing an outer end of said vane to an outersupport structure.
 25. A method according to claim 24, wherein saidouter end securing step comprises securing said outer end of said vaneto said outer support structure using threaded studs and nuts.